There's an active discussion on the Fedora mailing list concerning a "software center" for Fedora Linux.
A new Fedora contributor sparked a discussion about a software center for Fedora on this devel mailing list thread
He acknowledges there are nice user-interfaces for package management (gpk-application and Apper), but nothing really in the way of what Ubuntu Software Center has become. This person, Giovanni Campagna, goes as far as suggesting that the Ubuntu Software Center be ported to Fedora.
Feedback so far has been mixed with some Fedora developers not needing a reason to have a "software center" / "app store" and just mirroring features if Ubuntu has them.